Artificial target



April 21, 1964 Filed March 27, 1946 h IF 'lll/111111111111111 G. W.DOWNS ETAL ARTIFICIAL TARGET IQ smuLAToR sEcTloN Nose sEcTioN 4Sheets-Sheet l MAIN BODY GEORGE w. Downs RAYMOND n. ArcHLVEY www@ April21, 1964 G. w. DowNs ETAL A 3,130,384

ARTIFICIAL TARGET Filed March 27, 1946 4 Sheets-Sheet 2 AFTERBODY gmc/rmGEORGE w. Downs RAYMONDV o. ATcHLEY April 21, 1964 G. w. DOWNS ETAL`ARTIl-"ICIAL TARGET 4 Sheets-Sheet 3 Filed March 27, 1946 FIG. 2

' INVENToRs GEORGE w. DOWNS RAYMOND D. ATCHLEY ATTORNEY April 21,1964 G.w. DOWNS EII'AL ARTIFICIAL TARGET 4 Sheets-Sheet 4 Filed March 27, 1946INVENToRs'.

GEORGE W. DOWNS RAYMOND D. AT OHLEY a Attorney United States PatentOfiice 3,130,384 Patented Apr. 21, 1964 3,136,384 ARTIFICIAL TARGETGeorge W. Downs, Pasadena, and Raymond D. Atchley, San Diego, Calif.,assignors to the United States of America as represented by theSecretary of the Navy Filed Mar. 27, 1946, Ser. No. 657,584 Claims. (Cl.340-5) The present invention relates to the use of underwater sound insubmarine warfare.

A surface ship employs underwater sound to hunt down submarines. It notonly listens for the noise made by the propellers and gears of thesubmarine, but it also sends out pings, or short pulses of sound, sothat the submarine will send back echoes. These sound-guided attacks areso effective that submariners often prefer to evade, rather than meet,them.

Objects of the present invention include the provision of a device fordiverting anti-submarine attacks, the provision of a decoy thatsimulates the noises and sound characteristics of a submarine, theprovision of a self propelled decoy capable of being launched from asubmarine for facilitating an escape, and the provision of an improvedpractice target.

The target of the present invention is a small, self-propelled,torpedo-like submersible Craft, having automatic depth and coursecontrols. It is adapted to be launched from the torpedo tube of asubmerged submarine, and, after a short delay, to begin generatingnoises and repeating pings for simulating the self-noise and thesoundreilecting characteristics of a submarine. In combat, a submarinemay launch such a target to mislead an attacker and so facilitate itsown escape. As a practice target the device may be used for training thecrews of surface ships.

These and other objects and advantages of the present invention will beapparent from the following description of a specific embodiment of it.In the drawings:

FIG. l is an elevation, partly in section, of the device of the presentinvention.

FIG. 2 is an elevation, partly in section of a submarine torpedo tubewith the device of the present invention installed ready for launching.

FIG. 3 is a schematic diagram of the electrical system of the presentinvention.

FIG. 4 is a diagrammatic representation of part of the mechanism.

In FIG. 1 the assembly of the present invention consists of a nosesection 1d, simulator section 11, main body 12, and an after-body 13.These several units are joined with water tight seals and together theyform a cylindrical unit 70 inches long and six inches in diameter.Projecting from the top and bottom of the after body 13 are transducers14 and 16 that are a part of the echo repeater equipment, which will bedescribed presently. The overall height of the target at the transducersis slightly more than 20 inches, thus permitting the target to bereleased through a standard 21 inch torpedo tube. Anti-fouling cables 1Sextending from the tip of each transducer to the nose section 11Bprevent the transducers from catching on the submarine gear during thelaunching operation. Vertical stabilizer ns 20 and rudders 22 andsimilar horizontal controls (not shown) guide the target, and apropeller 5t) drives it.

The nose section is free flooding and contains a sea- `activated battery24 which generates 24 volts D.C. This battery furnishes all the powerfor the target.

The simulator section 11 contains a simulator motor 26 and a gear train28, which will be described presently. In the main body 12 is a sequencecontrol 3d, high voltage power supply 32, directional gyro 34, depthcontrol 36, and an electronic ampler 4t). Within the afterbody 13 is anelectric drive motor 46, and depth and course control solenoids 4S.

In FIG. 2 the target is shown installed in a submarine torpedo tube 52for launching. A clamp 54 secures the target to a roller 58 in thebottom of the tube. To launch the target the torpedo tube is irstflooded. The sea water activates battery 24 which generates 24 volts.

As is shown in FIG. 3, power is supplied immediately to the rotor 94 ofthe gyroscope 34 and to the heater of the thermal time-delay switch 70.This switch holds its contacts '72 open for approximately 60 seconds toprevent other units of the target from operating until the gyro rotor 94reaches its operating speed so that the target will have directionalstability when released. After switch '70 closes its contacts 72, thetarget is ready to be released from the torpedo tube.

The release cable 64 in FIG. 2 is wound onto reel 60 and thereby drawnthrough a packing in the breech door 62 of the torpedo tube. This actiondraws pin 56 to release the target from clamp 54, and also draws pin 66to close a release switch 45 which is shown in FIGS. l and 3.

In FIG. 3, contacts 72 of delay switch '70, and release switch 45 apply24 volts from the battery to the coil of relay 74. Relay '74 closes,locks in, and applies 24 volts to the heater of a second time delayswitch 76, to the heaters of the amplier 4d, to the depth control 36, tothe uncaging solenoid 99 of the gyro 34, to the course control relays 88and 9d, and to the drive motor 46. The drive motor 46 starts and turnsthe propeller 50 so that the target swims out of the torpedo tube andproceeds at a speed of approximately four knots. It is the purpose ofthe second time delay 76 to provide an interval between the releasing ofthe target and generation of simulated noises, during which the targetmay move far enough away from the launching submarine so thatreflections from the submarine will be too weak to sustain oscillationof the echo repeater. The mercury switches 84 and 85 of the depthcontrol 36 are operated by water pressure in a bellows 96, whichoperates against a spring 98 which regulates the movement of an arm 95that supports the mercury switches. The graduated dial 44 provides ameans oi regulating the force of said spring against the arm 95 forsetting the depth at which the target will operate. The mercury switchesS4 and 86 are so adjusted that they energize one or the other ofelevator solenoids 78 whenever arm 95 is 1 or more from a horizontalposition. Thus the mercury switches, by controlling the solenoids 78,will tend to regulate the angle of climb or dive of the target so as tohold the arm 95 in a level position. Should the target be launched from,or otherwise attain a depth that is not the same as the setting of theadjustment dial 44, the water pressure dierence in the bellows 96 willmove the arm d5 so that it lies at an angle above or below the axis ofthe hull. Thereupon the mercury switches 84 and Sd so control thesolenoids 78 as to maintain arm 95 in a level position and thereby putthe target into a climb or dive.

When the voltage is applied to the uncaging solenoid 99 it sets inoperation the directional stabilizing equipment. This releases the gyrosgimbals from the caging mechanisrn to allow the gyro to run free. Theuncaging mechanism is connected to a course setting dial 42 thatpre-sets the position in which the gyro will operate. A brush 91 isfastened to the outer gimbal and wipes a contacto; ring 93. When thetarget is oit the set course one segment of the contactor ring 93 is incontact with the brush 91, and power is supplied to the proper ruddersolenoid S0 through relay 88 or 9d to bring the target on course. Bymeans of the dial 42 the course of the beacon is adjustable up to leftor right of the heading of the target when released.

The second time delay switch '76 closes approximately 55 seconds afterthe target is released, and thereby closes relay 92 which connects+24'volts to the high voltage power supply 32 which supplies -l-B powerto the echo repeater amplifier 40. Relay 92 also supplies power to thenoise simulator rnotor 26which will be described presently. This actionthus puts the target into full operation.

A pressure operated safety switch 38 is provided in the negative powerlead that energizes relay 92. This switch opens when the target goesbelow a depth of 125 feet, and since relay 92 connects power to thenoise simulator motor 26 and echo repeater high voitage power supply 32,these units can be silenced in an emergency, if the target becomescaught on the submarine after launching, by diving to a depth in excessof 125 feet.

The simulator section 11 (FIG. l) consists of an electric drive motor 26and a gear train 28 that generate a gear whine and a propellercavitation noise that simulate the underwater sounds of a submergedsubmarine. In FIG. 4 the motor 26 of the simulator unit drives the gear100 at 1200 revolutions per minute (rpm.) to generate a gear whinehaving a fundamental frequency of 300 cycles per second. Every fourthtooth of the gear 100 is .010 inch higher than the other teeth. Thusduring each revolution of the gear fifteen high teeth are caused tostrike against two rollers 108 that are located diametrically on eitherside of the gear. These rollers 108 are mounted in hinged supports 110that transmit vibrations from the rollers to striking pads 1112, thatare adjusted to rest against the simulator case 106 so as to transmitthe vibrations to the sea water. A similar roller 114, and striking pad11e, are employed to generate a propeller cavitation noise of 120 beatsper minute. The roller being actuated by an eccentric gear 104 thatrotates 120 per minute. The gear 104 is .010 inch off center and inoperation only the high side of the gear strikes the roller 114 togenerate the simulated propeller cavitation noise. FIG. 4 isdiagrammatic in that it does not show the gears in the compact assemblythat is actually used.

Although here illustrated by a specific embodiment, the presentinvention should be limited only in accordance with the claims.

We claim:

1. In a self-propelled underwater decoy, an elongated hull havingpropulsion means, depth control for said hull comprising a hingedhorizontal fin attached to the stern of said hull and actuated by apressure-responsive device, directional control for said hull comprisinga hinged vertical n attached to the stern of said hull and actuated by agyroscope, a receiving transducer, an amplier and a transmittingtransducer carried by said hull to repeat sounds received by saidreceiving transducer, motor means driving a gear train positioned withinthe hull, and means bearing on the periphery of at least one of thegears in said gear train and mechanically connected to said hull so thatsaid hull is vibrated by rotation of said gear train and transmits soundwaves of a predetermined frequency to the surrounding water.

2. In a self-propelled underwater decoy having an elongated closedcasing, propelling means for said casing, motor means driving a dischaving a serrated periphery thereon, and means connected to a portion ofsaid casing and bearing on said periphery of said disc so that rotationof said disc vibrates said casing at a frequency determined by theperipheral speed of said disc and thereby causes said decoy to transmitto the surrounding water sounds similar to those normally produced by asubmerged submarine.

3. In an underwater self-propelled decoy having an elongated casing,propelling means for said casing, motor means driving a series ofintermeshed gear Wheels each revolving at a diiferent speed, firstmechanical means connected to said casing and bearing on one of saidgear wheels to vibrate said casing at one frequency, and secondmechanical means connected to said casing and bearing on a different oneof said gear wheels so as to vibrate the hull at a different frequency,said combined vibrations being designed to simulate the noise of asubmerged submarine.

4. In an underwater self-propelled decoy having an elongated casing, alongitudinal section of said casing being composed of thin elasticmaterial, propelling means for said casing, motor means driving a dischaving a serrated periphery with periodic serrations projecting to alarger radius than the remainder of said serrations, and mechanicalmeans secured to said longitudinal section and bearing on said periodicserrations so that said longitudinal casing is vibrated at a periodicrate by rotation of said disc.

5. A self-propelled underwater decoy adapted to be launched from asubmerged vessel, comprising an elongated hull, means for propelling thehull at a predetermined speed, means responsive to the pressure of thesurrounding water for maintaining the hull at a predetermined depth,means including a gyroscope for maintaining the hull on a predeterminedcourse with respect to the submerged vessel, echo producing apparatusincluding a receiving transducer, an amplifier and a transmittingtransducer carried by the hull for repeating each compressional waveimpinging on the receiving transducer a predetermined period of timeafter the compressional wave is received by said receiving transducer,means for generating a gear-whine within the hull having a predeterminedfundamental frequency, eans for periodically vibrating a portion of thehull so that it produces compressional waves in the sea water having afrequency designed to simulate compressional waves normally produced bysubmerged vessels, a second means for vibrating the hull at a frequencydifferent from that produced by said first hull vibrating means so as toproduce compressional waves in the sea water similar to those resultingfrom normal propeller cavitation of submerged vessels, means energizableby the surrounding sea water for generating power to drive thepropelling means, the gyroscope, the echo producing apparatus and thehull vibrating apparatus, and means for delaying the application ofpower to the echo apparatus and the hull vibrating apparatus for apredetermined period of time after the hull is propelled from thesubmerged vessel.

References Cited in the tile of this patent UNITED STATES PATENTS613,809 Tesla Nov. 8, 1898 1,427,560 Sperry Aug. 29, 1922 1,610,779Hewett Dec. 14, 1926 2,397,107 Hammond Mar. 26, 1946 2,397,844 DewhurstApr. 2, 1946 2,406,111 Sheteld Aug. 20, 1946 2,409,632 King Oct. 22,1946

2. IN A SELF-PROPELLED UNDERWATER DECOY HAVING AN ELONGATED CLOSEDCASING, PROPELLING MEANS FOR SAID CASING, MOTOR MEANS DRIVING A DISCHAVING A SERRATED PERIPHERY THEREON, AND MEANS CONNECTED TO A PORTION OFSAID CASING AND BEARING ON SAID PERIPHERY OF SAID DISC SO THAT ROTATIONOF SAID DISC VIBRATES SAID CASING AT A FREQUENCY DETERMINED BY THEPERIPHERAL SPEED OF SAID DISC AND THEREBY CAUSES SAID DECOY TO TRANSMITTO THE SURROUNDING WATER SOUNDS